This application is based upon and claims the benefit of priority from the prior Japanese Patent Application No. 11-140215, filed May 20, 1999, the entire contents of which are incorporated he rein by reference.
The present invention relates to a mechanism component design support system and a storage medium which stores a mechanism component design support program.
In recent years, demands have arisen for quick developments meeting ever changing consumer needs in product development operation. CAD systems for supporting design operations have received a great deal of attention under these circumstances. The CAD systems are mainly classified into a problem-oriented CAD system constructed to solve a certain problem and a general-purpose CAD system.
Problem-oriented CAD systems have often attained certain effects in business fields in which prototype designs are repeated. The problem-oriented CAD systems cannot support the design of industrial problems, particularly, in mechanism design departments because the life cycles of products are short and technical innovations are quick to come. Design knowledge is installed and hidden in a CAD system, so it is very difficult to perform maintenance and management such as knowledge updating and new registration.
The flow of mechanism design for, e.g., a camera will be described below. The use (basic concept) of a product is generally determined in a planning meeting. The design for a casing, mechanism, and software of the product is then started. Required specifications are determined for the respective units of a mechanism. The design aims at finding design solutions satisfying the required specifications.
FIG. 22 shows the design steps of mechanism units. First of all, a mechanism draft is created. That is, the mechanism draft for controlling the operations of all components is built into a skeleton model (the shapes of some components may be determined beforehand). The actual operation of the mechanism draft is confirmed on an illustration, and specifications satisfying the requirements as a mechanism are selected as a design draft at this stage (UGS: Imagination Engineer can be used).
An actual assembly is made up of a plurality of components. A set of components are extracted and combined to examine the shapes of the components and their limited motions. This combination is called a mechanism. Only the motion of the mechanism can be examined as a combination of points and lines, which generate identical limited motions because the materials, thicknesses, and the like of the components constructing the mechanism need not be considered. A model which represents a mechanism using only points and lines is called a skeleton (the OHM-Sha, Ltd., Shigeo Inada and Hitoshi Morita, xe2x80x9cUniversity Course, Study of Mechanismxe2x80x9d).
When the mechanism draft is confirmed using the skeleton model, the 2D shapes of components are then designed. The shape of some component may be determined by its function or by a combination with other components or units. When the outer shape of a given component is determined beforehand, a function as a mechanism for driving its shape is imparted to it using a skeleton model. A drafter or drafting CAD generally defines a 2D shape, and the operation of the defined 2D shape is checked with paperwork or a copy of the 2D shape. At this time, interference with other components is checked on the 2D model. The 2D shape is segmented (conventional drafting CAD can be used).
When the 2D shape of the component is determined, its 3D shape is then designed. Height (thickness) information as the third dimension is assigned to the 2D shape to design a 3D shape (projected drawing is created in drafting CAD). Interference with other components is checked on the 3D model, and the 3D shape is specified in its detail. As described above, each mechanism component is designed in 2.5D. A designer performs almost all these jobs on the drafter or 2D drafting CAD.
A 3D solid model is built using the components designed as described above, as needed. As a solid model creation method, manual manipulation or automatic creation on 3D CAD (Jpn. Pat. Appln. KOKAI Publication No. 8-335279) can be used.
In conventional design, a designer selects a mechanism draft and manipulates several parameters to select a design draft. In this case, a skilled designer can select an optimal solution in accordance with experience and intuition. An inexperienced designer requires many steps to obtain an optimal design draft. Design drafts selected by designers skilled and inexperienced alike are not always optimal. Large differences in design speed and quality occur due to the capabilities of designers.
Design defects such as interference of components, poor assembly properties, and sinkmarks and undercuts formed by a mold for injection molding often take place. This is because a system for systematizing design knowledge is absent, and knowledge once acquired cannot be used again. Many steps are required as a measure against repeated defects. Unsystematized knowledge adversely affects education of inexperienced designers.
The design operation contents have the following known individual tools.
Skeleton design: UGS: Imagination Engineer (trademark)
2D shape design: general 2D CAD system
3D shape design: general 2D CAD system general 3D CAD system
Since these systems are built as design supports for individual jobs, they cannot support the whole design consistently. Operation not directly related to the design, i.e., data conversion between systems, must be performed. This operation is inefficient to shorten the design period. Designer""s knowledge is difficult to input and edit, and the system knowledge is also hidden. It is therefore difficult to use new knowledge and refer to the details of past knowledge.
An example of a component layout/assembly job efficiency improving support system is disclosed in xe2x80x9cJpn. Pat. Appln. KOKAI Publication No. 10-254939: Mechanism Design Support Apparatus and Methodxe2x80x9d or the like. Although a support for creating a component shape in combination with other components has been established, no support is available to generate a mechanism draft in entirely new design. A person who actually build a 3D component model is a designer himself, and a large number of design steps are required.
Design books and magazines published as design results contain information of working methods, materials, and tolerances in addition to component shapes. However, such information cannot be added to data or used again because the current 2D CAD system processes the information merely as a character string and the 3D CAD system processes only shapes.
Assume that a mechanism component is prepared using a mold. If a thickness is simply added to a 2D structure, the resultant mechanism component may not be releasable from the mold. To prevent this, a draft angle may be imparted to the mold. It is, however, very cumbersome to perform a new design for defining the draft angle in the mold.
The present invention has been made in consideration of the above situation, and has as its object to provide a mechanism component design support system capable of optimal designing within a short period of time regardless of the skills of designers and allowing reuse of knowledge.
It is another object of the present invention to provide a storage medium which stores a mechanism component design support program for implementing the above mechanism component design support system in a computer.
A design support system of the present invention comprises: a mechanism object library for storing knowledge for defining, on the basis of assembly structure information, a plurality of mechanism components usable in a skeleton model; an examination unit for inputting a mechanism draft for achieving a specified object, using the skeleton model, and examining a function of the skeleton model; a two-dimensional shape editor for generating and optimizing, on the basis of required specifications of the mechanism draft, a two-dimensional shape of a mechanism component selected from said mechanism object library; and a model database for redefining, using the assembly structure, an attribute which is output from said two-dimensional shape editor and defines the mechanism component, and storing the redefined attribute, and wherein the attribute of the mechanism component is solely managed on the basis of the assembly structure information.
According to the present invention, mechanism component information is solely managed with an assembly structure. Systematic mechanism component design can be supported, which includes: generation of a mechanism draft using a skeleton model in selecting the mechanism draft and a mechanism operation simulation for the mechanism draft; a mechanism operation simulation in a state in which some (or all) 2D shape are determined; and then automatic generation of a 3D shape and a mechanism operation simulation for the 3D shape. An optimal design can be performed within a short period of time regardless of the skills of designers, and knowledge can be used again.
Additional objects and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out hereinafter.